Reinforced electromechanical actuator housing

ABSTRACT

An electromechanical actuator housing assembly comprising a reinforcement ring is disclosed herein. The design of the electromechanical actuator housing assembly may be directed to improving load measurement accuracy. The design of the electromechanical actuator housing assembly may be directed to reducing housing deflections. A method of manufacture of an EMA housing assembly is also disclosed herein. This method may include an electromechanical actuator housing assembly having a reinforcement ring.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. Ser. No. 13/922,590, filed Jun.20, 2013, entitled “REINFORCED ELECTROMECHANICAL ACTUATOR HOUSING”,which is which is hereby incorporated by reference in its entirety.

FIELD

The present disclosure is related to electromechanical actuators, andmore particularly, to an electromechanical actuator housing assembly foruse in an aircraft brake.

BACKGROUND

Electro-mechanical Actuators (EMAs) have been an emerging technology forthe last decade in the aerospace brake controls industry. A focus onlightweight components is a constant driving force for aerospacesystems. Improved performance and reliability is also desired whendesigning new aircraft braking systems and elements thereof. Thehousings that protect these actuators benefit from thoughtful design tomeet customer requirements (e.g., strength, weight, size, etc.).

SUMMARY

The present disclosure relates to an electromechanical actuator housingassembly designed to address, among other things, the aforementioneddeficiencies and attributes in prior art EMA housing assemblies. Systemsand methods disclosed herein may be useful in connection with anelectromechanical actuator housing assembly. EMAs described herein maycomprise a reinforcement ring. Embodiments described herein may bedirected to improving load measurement accuracy and extending servicelife of the housing. Embodiments described herein may be directed toreducing housing deflections and stresses.

A method of manufacture of an EMA housing assembly is also disclosedherein. This method may include manufacture of an electromechanicalactuator housing assembly having a reinforcement ring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an isometric view of the top portion of aconventional EMA housing having no reinforcement ring;

FIG. 1B illustrates a cut-away view of the EMA housing of FIG. 1A;

FIG. 1C illustrates a cut-away view of a conventional EMA housing havingno reinforcement ring;

FIG. 2 illustrates a cut-away view of an EMA housing having areinforcement ring in accordance with embodiments of the presentdisclosure;

FIG. 3 illustrates a cut-away view of an EMA housing depicting referenceplane C-C′ in accordance with embodiments of the present disclosure;

FIG. 4A illustrates an isometric view of the top portion of an EMAhousing having a reinforcement ring in accordance with variousembodiments of the present disclosure; and

FIG. 4B illustrates a cut-away view of the EMA housing of FIG. 4A.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration and their best mode. While these exemplary embodiments aredescribed in sufficient detail to enable those skilled in the art topractice aspects of the disclosure, it should be understood that otherembodiments may be realized and that logical, chemical and mechanicalchanges may be made without departing from the spirit and scope of thedisclosure. Thus, the detailed description herein is presented forpurposes of illustration only and not of limitation. For example, thesteps recited in any of the method or process descriptions may beexecuted in any order and are not necessarily limited to the orderpresented. Furthermore, any reference to singular includes pluralembodiments, and any reference to more than one component or step mayinclude a singular embodiment or step. Also, any reference to attached,fixed, connected or the like may include permanent, removable,temporary, partial, full and/or any other possible attachment option.Additionally, any reference to without contact (or similar phrases) mayalso include reduced contact or minimal contact.

Systems and methods disclosed herein may be useful for electromechanicalactuator assemblies. Although the embodiments herein are described withreference to electromechanical actuator assemblies used in connectionwith aircraft brakes, such embodiments are provided for example only asit is contemplated that the disclosures herein have applicability toother electromechanical actuators and their uses.

EMAs often utilize load cells. A load cell is a device that measures aload. Generally, the quality of the control surface where the load cellis positioned is directly associated with the accuracy of the loadcalculation/measurement. At times, this measurement is affected bydeflection and/or altering/bending of an EMA housing and/or othermeasurement surface. This deflection of an EMA housing may bereactionary.

EMAs are often used in braking systems, such as aircraft brakingsystems. With momentary reference to FIG. 2, deflection of aspects ofthe system, such as surface 130 and/or EMA housing assembly 100,generally leads to inaccurate load cell measurement and may adverselyaffect dynamic braking response. Thus, the braking response time may bedecreased as deflection is reduced. Stated another way, the time ittakes for the brakes to function may be decreased. Also, a stiffersystem may result as deflection is reduced. Similarly, as deflectionsare reduced, housing assembly 100 may be made smaller which reducesweight.

Accurate load cell measurements are difficult to achieve with theconventional EMA housing designs (See FIGS. 1A-1C). FIGS. 1A through 1Cshow an EMA housing without a reinforcement ring atop the housing. Ithas been observed that the load cells of these conventional EMA housingshave been subject to drift errors which then leads to re-trimming in theassembly to regain the desired load measurement accuracy. Housingdeflections are a primary reason for these inaccuracies.

According to various embodiments and with reference to FIG. 2, an EMAhousing assembly 100 in accordance with the present disclosure comprisesa reinforcement ring 120. Axis A to A′ is shown for reference. Point A′may be referred to as distal to point A′ and point A may be refereed toas proximal to point A.

As used herein, a reinforcement ring may be as any housing geometry thatlies distal to the retaining surface, such as surface 130, of the EMAhousing that decreases in axial distance from the mounting flange 150while moving towards the axial centerline A-A′ as measured from theexterior, such as surface 160, of the EMA housing. Similarly,reinforcement ring 120 changes in radial length as one moves proximallyalong axial centerline A-A′. With momentary reference to FIG. 3,reinforcement ring 120 comprises a housing geometry that varies aboveand below a plane, such as plane C, which is perpendicular to the axialcenterline A-A′ of the EMA housing (see FIG. 3). For instance, portionsof the reinforcement ring 120 extend above plane C-C′, while portions ofreinforcement ring 120 do not reach plane C-C′. For instance, portionsof the reinforcement ring 120 extend above plane C-C′, while portions ofreinforcement ring 120 do not reach plane C-C′. Reinforcement ring 120may comprise a housing geometry that varies in radial distance fromaxial centerline A-A′ along two parallel planes which are perpendicularto the axial centerline A-A′ of the EMA housing. According to variousembodiments, reinforcement ring 120 may be integrally formed in thehousing assembly 100 located above retaining surface 130. Top surface140 of reinforcement ring 120 may comprise a housing geometry whichslopes in a proximal and/or downward direction moving towards the axialcenterline A-A′ of the EMA housing.

With renewed reference to FIG. 2, Length Y^(2′) illustrates length ofreinforcement ring 120 as measured at its longest distance. The totalaxial distance of EMA housing assembly 100 is Y²+Y^(2′), where Y² is theaxial distance from mounting flange 150 to the top surface 140 aboveretaining surface 130 of EMA housing assembly 100. Reinforcement ring120 does not have to add to overall EMA housing length as compared withconventional EMA housings, such as the EMA housings of FIGS. 1A-1C.Stated another way, in various embodiments, Y²+Y^(2′) may be equal to orless than Y¹ (See FIG. 1C).

As a comparison, the EMA housing in FIG. 1C does not have any geometrythat decreases in axial distance while moving towards the EMA axialcenterline A-A′ as measured from the exterior of the EMA housing. Statedanother way, top surface 145 of the EMA housing of FIG. 1 issubstantially flat with no variation in axial length across its surface.In contrast, top surface 140 of EMA housing assembly 100 in FIG. 2 hasgeometry that decreases in axial distance while moving towards the EMAaxial centerline A-A′.

Also, as a comparison, the portion of the EMA housing between topsurface 145 and retaining surface 135 as shown in FIGS. 1A-1C, extendsfurther towards the EMA axial centerline A-A′ as compared with theportion of the EMA housing assembly 100 between top surface 140 andretaining surface 130 as shown in FIG. 2. Stated another way, EMAhousing assembly 100 comprises less material between retaining surface130 and top surface 140, at its smallest measured axial length,extending towards axial centerline A-A′ as compared with conventionalEMA housing assemblies.

EMA housings in accordance with the present disclosure tend to reducethe probability of experiencing degraded load cell performance bydecreasing housing deflections. Also, a device, such as a washer 115,generally located adjacent to a load cell sensor towards the bottom ofthe housing (surface 130), is no longer required as compared withwashers 115 in prior EMA assemblies. This eliminates previous steelwashers 115 utilized, which could be approximately ½ inches (1.27centimeters) thick. This device/washer 115 may spread the load of theactuator to the housing and make the assembly more stiff to address,restrict and/or prevent deflections. This may assist in more accuratereadings of the load cell, as thicker washers 115 may contribute toinconsistent readings as well as increase the mass and size of theconventional EMA housing assemblies. Also, due to the elimination of thewasher 115, the overall EMA housing assembly 100 size may be reduced.This size reduction of the EMA housing assembly is highly desired byaerospace customers as weight of materials is a premium.

While not intending to be bound by theory, finite element modelsindicate an approximate 18.9% reduction in stress when using thereinforcement ring 120 design as compared to conventional designs. Also,the reinforcement ring 120 design may contribute to a negligible weightincrease as compared to the non-reinforcement ring design, such as anincrease in the the weight of the EMA housing assembly 100 by about0.005 lbs (about 0.002268 kilograms) (less than 0.056%).

According to various embodiments, in a conventional EMA housing withouta reinforcement ring, at 8,500 lbs actuation load, a measured maximumstress may be 44.9 ksi (309.6 megapascal). Also, the maximum measureddeflection in inches may be 0.0141. In contrast, in EMA housing assembly100 comprising reinforcement ring 120, at 8,500 lbs actuation load andmade of the same material as the prior example, the maximum stressmeasured was 38.7 ksi (266.8 megapascal). Also, the maximum deflectionmeasured in inches is 0.0084. Thus, in this case the percentagereduction in deflection by EMA housing assembly 100 over conventionaldesigns (those not having a reinforcement ring) is 41 percent. Also,reduction in system stress is achieved with the designs describedherein. For example, EMA housing assembly 100 may represent a reductionin system stress of between about 5 and 25 percent, between about 10 and20 percent, and/or between about 12 and 15 percent. According to variousembodiments, a reduction in system stress is 14 percent.

The deflection of EMA housing assembly 100 is also reduced by nearly 50%as compared with conventional EMA housing assemblies. A lower amount ofdeflection tends to greatly improve the amount of load cell gain as wellas the accuracy of the load cell inside EMA housing assembly 100 by notintroducing off axis loading. This improves the function of EMA housingassembly 100 and the performance of the brake control system itsupports. Thus, the performance of EMA housing assembly 100 is improvedwithout increasing the weight or only slightly increasing the weight ascompared with other EMA housings.

According to various embodiments, and though it may be made from anysuitable material, EMA housing assembly 100 comprises at least one of aforged aluminum housing, steel housing, machined carbon composite,and/or the like. A forged aluminium housing keeps stress levels to thosethat meet EMA housing life goals as well as achieves a reduction of EMAweight compared to that of a steel housing.

According to various embodiments and with reference to FIGS. 4A and 4B,EMA housing assembly 100 may comprise an aperture 170 configured toreceive a data acquisition unit (ADU) motor housing, and restrict orprevent its rotation which may be secured using a motor retention nut.Aperture 170 may be defined as a surface that bounds a cavity of EMAhousing assembly 100. Aperture 170 may be sized such that the ADU motorretention nut be embedded in the EMA housing such that a portion of themotor retention nut is positioned proximal to top surface 140 of EMAhousing assembly 100. Aperture 170 may be sized such that, in responseto being properly installed, substantially all the ADU motor retentionnut is positioned proximal to top surface 140 of EMA housing assembly100. Aperture 170 may be shaped such that its perimeter is complementaryto the exterior surface of the ADU motor retention nut. The ADU motorretention nut may be moved (e.g. tightened/removed) through the use of aspanner nut tool or other suitable device.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the inventions. The scope of the inventions is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”, “anexample embodiment”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112, sixth paragraph, unless the element isexpressly recited using the phrase “means for.” As used herein, theterms “comprises”, “comprising”, or any other variation thereof, areintended to cover a non-exclusive inclusion, such that a process,method, article, or apparatus that comprises a list of elements does notinclude only those elements but may include other elements not expresslylisted or inherent to such process, method, article, or apparatus.

1. A method of manufacture of an EMA housing assembly, comprising: forging an aluminum housing of an electromechanical actuator having a reinforcement ring integrally coupled to the EMA housing, wherein the reinforcement ring comprises a housing geometry with material lying distal to a retaining surface of the EMA housing that decreases in axial distance as measured from a mounting flange while moving towards an axial centerline as measured from an exterior surface of the EMA housing.
 2. The method of claim 1, wherein the reinforcement ring is configured to reduce deflections of the EMA housing assembly.
 3. The method of claim 1, wherein the reinforcement ring is configured to reduce inaccurate measurements of a load cell coupled to the EMA housing assembly.
 4. The method of claim 1, wherein the reinforcement ring is configured to stiffen a braking system associated with the EMA housing assembly.
 5. The method of claim 1, wherein the EMA housing assembly comprises aperture surface that bounds a cavity configured to receive an ADU motor retention nut.
 6. A method of manufacture of an EMA housing assembly, comprising: forging a housing of an electromechanical actuator having a reinforcement ring integrally formed in the housing assembly with a retaining surface located axially between the reinforcement ring and a mounting flange of the housing assembly, wherein the retaining surface comprises a polygonal geometry, wherein the reinforcement ring is disposed distal to the mounting flange of the housing assembly, and wherein the reinforcement ring has a tapered geometry.
 7. The method of claim 6, wherein the reinforcement ring comprises a housing geometry that varies across two parallel planes perpendicular an axial centerline of the EMA housing.
 8. The method of claim 6, wherein a surface of the integral reinforcement ring comprises an exposed surface of the EMA housing assembly.
 9. The method of claim 6, wherein the maximum stress of the EMA housing assembly measured at 8500 lbs actuation load is less than or equal to 38.7 ksi.
 10. The method of claim 6, wherein the EMA housing assembly is installed on an aircraft.
 11. The method of claim 6, wherein the EMA housing assembly is forged of aluminum.
 12. The method of claim 6, wherein the EMA housing assembly is forged of steel.
 13. A method of manufacture of an EMA housing assembly, comprising: machining a housing of an electromechanical actuator having a reinforcement ring integrally formed in the housing assembly located above a retaining surface, wherein the top surface of the reinforcement ring comprises a housing geometry which slopes in a proximal direction moving towards the axial centerline of the EMA housing.
 14. The method of claim 13, wherein the reinforcement ring comprises a housing geometry that varies across two parallel planes perpendicular an axial centerline of the EMA housing.
 15. The method of claim 13, wherein a surface of the integral reinforcement ring comprises an exposed surface of the EMA housing assembly.
 16. The method of claim 13, wherein the maximum stress of the EMA housing assembly measured at 8500 lbs actuation load is less than or equal to 38.7 ksi.
 17. The method of claim 13, wherein the EMA housing assembly is installed on an aircraft.
 18. The method of claim 13, wherein the EMA housing assembly is machined of carbon composite. 